Scroll apparatus for fluid compression or expansion is typically comprised of two upstanding and interleaved involute wraps. Each involute wrap extends from an end plate and has a tip disposed in contact or near-contact with the surface of the end plate from which the other scroll wrap extends. Each scroll wrap also has flank surfaces which adjoin in moving line contact, or near contact, with the flank surfaces of the other scroll wrap to define, in cooperation with the scroll end plates, a plurality of moving chambers.
Depending upon the direction of orbital motion of the scroll wraps, the chambers move radially inward from the exterior of the interleaved scroll wraps for fluid compression or radially outward from the interior of the interleaved wraps for fluid expansion. The scroll wraps, in order to accomplish the formation and movement of the chambers, are placed in relative orbital motion by a drive mechanism.
Several attempts have apparently been made to develop co-rotational scroll apparatus. Such apparatus provides for concurrent rotary motion of both scroll wraps on parallel offset axes to generate the requisite orbital motion between the wrap elements. However, most scroll apparatus to date and compressors in particular have been of the type having one fixed and one orbiting scroll due to various and many difficulties and complexities associated with co-rotating scroll apparatus. In that regard, no commercially available co-rotating scroll compressors are known to exist despite the many theoretical advantages offered by a co-rotating scroll compressor over a scroll compressor of the type in which one of the scroll members is fixed.
Notable with respect to Background Art are U.S. Pat. Nos. 801,182; 3,600,114 and 4,178,143. The '182 patent teaches the concept of co-rotating scroll apparatus and indicates that the basic concept is relatively old. The '114 and '143 patents are suggestive of other still relatively early attempts to design co-rotating scroll apparatus although, in each case, apparatus the purpose of which is to act as a pump or a motor rather than as a compression apparatus.
Also noteworthy is an effort undertaken by Sundstrand Corporation, as evidenced by a series of patents issuing in the mid-1980's to develop co-rotating scroll compression apparatus. Of particular note with respect to the present invention is Sundstrand's U.S. Pat. No. 4,600,369 which is discussed below.
More recently, interest in the commercialization of co-rotating scroll apparatus has been evidenced by the patent activity of the assignee of the present invention, Arthur D. Little Inc. and Mitsubishi Denki. Several other internationally known business entities have indicated an interest in developing co-rotating scroll compressor technology as evidenced by the issuance of patents in the U.S. and foreign countries. Co-rotating scroll technology would therefore appear to be poised for rapid and extensive international development and commercialization although, once again, no commercially available co-rotating scroll compression apparatus are known to be available as of the filing date hereof. With respect to the present invention, the following patents are deemed to be of interest.
U.S. Pat. No. 4,600,369 discloses one biasing arrangement for counteracting the pressure developed in the compression chambers defined by the scroll wraps of a co-rotating scroll compressor. That pressure tends to force the two scrolls axially apart thereby encouraging leakage and a loss in compressor efficiency. The arrangement of the '369 patent includes an element which rotates with the idler scroll member and which defines a pressure chamber for urging the scroll members axially together against the pressure developed in the compression chambers between the scroll members. The element carries a set of seals which bear against the driven scroll member to seal the pressure chamber.
U.S. Pat. No. 4,927,339, assigned to the assignee of the present invention and incorporated herein by reference, likewise discloses various arrangements in co-rotational scroll apparatus for axial biasing scroll members toward each other including arrangements making use of a biasing element which rotates with the drive scroll member.
U.S. Pat. No. 5,129,798, likewise assigned to the assignee as the present invention and incorporated herein by reference, provides for improved biasing of the idler scroll toward the drive scroll in co-rotational scroll apparatus. In the '798 patent, a pressure plate carried by the drive scroll is disposed adjacent the underside of the idler scroll end plate. A seal, carried by the idler scroll, is disposed in a recess in the underside of the idler scroll end plate and is controllably pressure biased into engagement with the pressure plate thereby biasing the idler scroll toward the drive scroll.
U.S. Pat. No. 5,212,964, assigned to the assignee of the present invention, meets, on the other hand, the need for lubrication between the tips of the involute wraps of the drive and idler scrolls and the opposed end plates. Pickup tubes that rotate with the idler scroll member direct lubricant from a lubricant sump to a passage in the end plate of the idler scroll. The lubricant flows radially outward in the passage and is discharged through a port defined on the involute wrap side of the end plate of the idler scroll member so as to lubricate the interface between the tip of the drive scroll involute wrap and the end plate of the idler scroll.
Notwithstanding the above noted improvements in the design of co-rotating scroll apparatus and the teachings of the above-mentioned patents, there remains a need to provide for adequate lubrication in such a compressor, including lubrication of the seal in axial pressure biasing arrangements, a need to protect that seal from potentially damaging debris and a need to simultaneously provide adequate lubrication to bearings and other surfaces within the apparatus, before commercialization of such apparatus becomes viable.
Therefore, it is an object of the present invention to provide co-rotational scroll apparatus having improved lubrication and an axial pressure biasing arrangement which minimally effects the overall efficiency of the apparatus.
It is yet another object of the present invention to provide a co-rotational scroll compressor in which a controlled, effective and adequate flow of lubricant therethrough is maintained, including lubricant flow to the compressor's bearings, scroll member interface surfaces and the seal in the compressor's axial pressure biasing arrangement.
It is yet another object of the present invention to provide a scroll compressor where a pressure biasing seal is provided lubrication and is protected from potentially damaging debris, all in a manner which is efficient and relatively inexpensive to implement.
These and other objects of the present invention will be apparent from the attached drawings and the Description of the Preferred Embodiment which follows.